The Radiation Oncology Branch has continued studies using iododeoxyuridine given by continous intravenous infusion for 24 hours daily for up to 14 days in patients with high-grade primary brain tumors and other poorly radioresponsive tumors. The treatment protocol involves two separate, two-week infusions of IUdR combined with twice daily radiation therapy. Approximately 60 patients have been entered on the trial using the continuous intravenous infusion, including 36 patients with glioblastoma multiforme. The maximal tolerable dose of IUdR given as a continuous intravenous infusion for 24 hours a day for up to 2 weeks, is 1000 mg/m2/day. Dose-limiting systemic toxicity is thrombocytopenia. There appears to be an improvement in median survival in glioblastoma patients compared to historical controls with a median survival approaching 14 months. Additionally, in patients with large, unresectable sarcomas, local control. has been achieved in 12 of 15 patients. Again, this represents an improvement in local control of large, unresectable sarcomas compared to historical controls.